PLC-based wind­ing application

Aaron Laufs has very successfully implemented the outsourcing of a control system for winding systems to a programmable logic controller as part of his bachelor thesis.
Aufbau der Wickelapplikation

Aaron Laufs has very suc­cess­ful­ly imple­ment­ed the out­sourc­ing of a con­trol sys­tem for wind­ing sys­tems to a pro­gram­ma­ble log­ic con­troller as part of his bach­e­lor the­sis. A wind­ing mod­el with dancer and ten­sion con­trol, which was equipped with sys­tem com­po­nents from our pre­mi­um sys­tem part­ner Mit­subishi Elec­tric, is used to ana­lyze and apply the devel­oped software.

Moti­va­tion and background

In a pre­vi­ous bach­e­lor the­sis, we designed and imple­ment­ed the mod­el of the wind­ing sys­tem with PLC-based con­trol. The exist­ing test mod­el has now been mod­i­fied and equipped with soft­ware and hard­ware from Mit­subishi Elec­tric. “Togeth­er with Mit­subishi, I have devel­oped a con­trol basis for wind­ing appli­ca­tions that can be used flex­i­bly in the future for dif­fer­ent motor and sys­tem sizes,” reports Aaron.

With this bach­e­lor’s the­sis, Aaron Laufs grad­u­at­ed sum­ma cum laude from Aachen Uni­ver­si­ty of Applied Sci­ences in the field of automa­tion and dri­ve tech­nol­o­gy. After his appren­tice­ship and ini­tial work expe­ri­ence, Aaron decid­ed to study full-time, which led him to QA in the mid­dle of last year. After his intern­ship semes­ter and his bach­e­lor the­sis at QA, Aaron will start his mas­ter stud­ies in the com­ing semes­ter. We would like to wish him every suc­cess and are already look­ing for­ward to an excit­ing mas­ter’s thesis.

The test setup

The mod­el made of Fis­chertech­nik com­po­nents sim­u­lates almost real con­di­tions. A feed unit in the mid­dle between the two wind­ing units sets the speed. On the left side, a dancer con­trol is imple­ment­ed. In this process, the mate­r­i­al is guid­ed behind the winder via a ver­ti­cal­ly freely mov­able dancer. If pos­si­ble, the dancer should always remain in a cen­tral posi­tion, and the con­trol sys­tem reacts to devi­a­tions from this posi­tion. The path is mea­sured by a slid­ing poten­tiome­ter. For the sec­ond method, ten­sion con­trol, a fixed deflec­tion roller is used, with force sen­sors attached to its foun­da­tion. Here, the ten­sion on the roller defines the con­trolled variable.

Process con­trol and soft­ware design

The entire process con­trol is car­ried out in the dig­i­tal domain and thus pos­es cer­tain chal­lenges for a func­tion­ing con­trol. The ana­log sig­nal is first dis­cretized with respect to the sam­pling time, which allows a snap­shot at fixed time inter­vals. Sub­se­quent­ly, the con­ver­sion into a dig­i­tal val­ue takes place. Great demands are placed on data pro­cess­ing and trans­mis­sion in par­tic­u­lar, since syn­chro­nous pro­cess­ing of the data must be ensured with­in the dig­i­tal con­trol. This is the only way to ensure a time-con­tin­u­ous out­put of the manip­u­lat­ed vari­able.
The dancer and ten­sion con­trol was imple­ment­ed as feed­for­ward con­trol. On the one hand, this has the advan­tage that the con­troller is relieved, since only exist­ing con­trol devi­a­tions have to be com­pen­sat­ed. On the oth­er hand, the improve­ment of the dynam­ic behav­ior results in a faster reac­tion to changes in the ref­er­ence vari­able or dis­tur­bance vari­able. In order to be able to use the feed­for­ward con­trol, all phys­i­cal rela­tion­ships with­in the appli­ca­tion had to be deter­mined. These includ­ed the wind­ing diam­e­ter, the web speed, the ten­sile force and the torque. To map the phys­i­cal process­es, new func­tion blocks had to be cre­at­ed that real­ize the cal­cu­la­tion of the required vari­ables. These include, for exam­ple, the diam­e­ter cal­cu­la­tion of the wind­ings, fric­tion com­pen­sa­tion and torque pre­con­trol. The PI con­troller was real­ized with a Mit­subishi module.

Results and fur­ther appli­ca­tion areas

The ten­sion con­trol has a very good con­trol behav­ior, the ref­er­ence vari­able is reached after about one sec­ond. The accu­ra­cy of the com­mand behav­ior is ±(13.9 ± 8.66) mN (max. con­trol devi­a­tion ± accu­ra­cy of mea­sur­ing sys­tem). The dancer con­trol has an accu­ra­cy of ± 3.2 mm. It should be not­ed here that the dancer is an inert sys­tem, so that changes in the manip­u­lat­ed vari­able can only be detect­ed in the sys­tem with a delay. The good con­trol behav­ior ensures that dis­tur­bance vari­ables are quick­ly com­pen­sat­ed for. In par­tic­u­lar, ten­sion con­trol ensures high accu­ra­cy of the ten­sion force and should accord­ing­ly be used for such appli­ca­tions.
With regard to PLC-based con­trol, the devel­oped appli­ca­tion offers a wide range of appli­ca­tion areas. How­ev­er, the laten­cy of the bus sys­tem and the PLC in rela­tion to the required process must always be tak­en into account here.
Fur­ther­more, the devel­oped func­tion blocks can also be used on oth­er con­trol plat­forms, which is made pos­si­ble by the open source pro­gram­ming. The devel­op­ment of the essen­tial func­tion blocks for the appli­ca­tion was real­ized inde­pen­dent of the man

Process data mon­i­tor­ing through MQTT connection

By imple­ment­ing an MQTT card, process data mon­i­tor­ing via web inter­face was cre­at­ed using Mosquit­to as MQTT serv­er. On a web­site pro­grammed with HTML, CSS and JavaScript, among oth­er things, the ten­sile force, the diam­e­ter and the plant sta­tus can be monitored.